On Sep 7, 2009, at 12:06 AM, I wrote:
> On Sep 6, 2009, at 11:51 PM, Mark Lause wrote:
>>>> So, there WERE many female contemporaries "Eve." They had kids. We
>> are also their descendants. We just don't have their mitochondrial
>> DNA, because--at some point--those lines came to an end.
> But what is the probability that, out of an interbreeding population
> large enough to speciate, all but *one* maternal line will gradually
> become extinct? Darwinian evolution can't handle the phenomenon of
> extinction by relying only on gradual processes...
On Sep 7, 2009, at 12:18 AM, Mark Lause wrote:
> Of course it can, Shane.
>Dinosaurs were extincted gradually? American horses, elephants, and
camels?
> The way to think of this is to go back before the "Eve" and ask how
> those lines disappeared. Every time a new human is created, it'll have
> the mitochondrial DNA of its mother's mother and that of its father's
> mother isn't passed on. Every role of the dice loses 50%. So, over
> time, the probability of having "lines" disappear are much higher than
> surviving.
>But speciation involves a growing population. In a population *large
enough for Darwinian speciation to occur* and with each generation
containing roughly equal numbers of males and females, a certain
proportion of mothers will have multiple reproducing daughters, some
only one, some none. So statistically some lines will go out while
others multiply. The number of lines will dwindle, but each surviving
line will have more members and that makes the probability of its
disappearance dwindle with each generation. How small, then, must
the original population be for there to be more than virtually no
chance that *all but one* of the original lines will disappear?
Humans did not descend from a single female or small group on an
isolated island, like the Galapagos finches. They evolved in a large
continent with a large prehuman population.
> ...human populations have always been extremely small until quite
> recently in
> the grand scheme of things. So in the thousands of years before the
> mitochondrial "Eve," those lines fall victim to the statistics...
But "small...in the grand scheme of things" does not mean absolutely
so small that random survival rates will gradually extinguish *all but
one line*. That is why the "mitochondrial Eve" hypothesis is in
contradiction to the "Darwinian gradual evolution" hypothesis of human
origins. And the contradiction is crucial, because the hypothesis of
constancy for the rate of change in mitochondrial DNA depends on the
assumption of constancy in the environmental conditions determining
that rate of change, and such gradualism would guarantee the survival
of more than one line unless the original population was too small for
Darwinian speciation to occur in the first place.
The point is *only* this--the "mitochondrial Eve" hypothesis is only
one, and very far from the most solid, piece of evidence pointing to
the falsity of gradualism as explanation for the evolutionary process.
Shane Mage
> This cosmos did none of gods or men make, but it
> always was and is and shall be: an everlasting fire,
> kindling in measures and going out in measures."
>> Herakleitos of Ephesos